def f(n):
    d = 2
    while d * d <= n:
        if n % d == 0:
            return False
        d += 1
    return True

d = ['zero', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine']
a = input().split()
if len(a) !=3 or a[0] not in d or a[1] not in d or a[2] not in d:
    print('Wrong input')
else:
    n = int(str(d.index(a[0])) + str(d.index(a[1])) + str(d.index(a[2])))
    for i in range(1,1000):
        if f(n-i):
            print(n-i)
            break
        if f(n+i):
            print(n+i)
            break